KR100421478B1 - Integrator of Illumination Optic System of Apparatus Projecting Image - Google Patents

Abstract

The present invention relates to an integrator of an illumination optical system of an image display device for improving light efficiency.

The integrator of the image display apparatus illumination optical system according to the present invention includes a light incident surface to which light is incident, a light exit surface to which the light is emitted, and at least two inclined surfaces having different inclinations. The inclined surfaces having different inclinations are connected with a step, and the light incident surface is larger than the light emitting surface.

By such a configuration, the integrator of the image display apparatus illumination optical system according to the present invention can improve the light efficiency.

Description

Integrator of Illumination Optic System of Apparatus Projecting Image}

The present invention relates to an integrator of an image projection apparatus illumination optical system, and more particularly to an integrator of a liquid crystal projection apparatus illumination optical system that can improve the light efficiency.

Recently, with the rapid increase in the number of projectors, various projector products have been developed. In general, projectors are widely used for business purposes, mainly for presentation purposes. These projectors are on the trend to be compact, light weight and light, so as to be portable.

Liquid crystal displays (hereinafter referred to as "LCD") and digital micromirror devices (hereinafter referred to as "DMD") are widely used as display elements widely used in such projectors. LCDs can be classified into transmissive and reflective LCDs, and transmissive LCDs are mainly used. In the transmissive LCD, the state of the liquid crystal changes according to an electrical change applied from the outside, and the amount of light transmitted is controlled according to the state of the liquid crystal. That is, the transmissive LCD is a kind of light valve display element whose light intensity is changed by electrical control.

In contrast, DMDs are used in digital light processing ("DLP") systems. The DMD is an optical switch display device that converts the reflection angle of light into two modes by changing the tilt angle of the micromirror to +10 to -10 degrees.

1 is a diagram illustrating driving characteristics of a DMD.

Referring to FIG. 1, first, a DMD includes a plurality of electrodes 3 provided at predetermined portions on a black board 1, a micromirror 5 for reflecting light emitted from a light source 9 at a predetermined angle; And a shaft 7 for supporting the micromirror 5.

The light from the light source 9 is not reflected toward the projection lens 11 by the micromirror 5 set at an initial predetermined angle, but is absorbed toward the absorption plate 13 so that the screen 15 becomes black. Applying a voltage generates an electric field on the plurality of electrodes 3 provided on the black board 1. The shaft 7 connected between the adjacent electrodes 3 is moved at a predetermined angle by the electric field generated by the electrodes 3. The micromirror 5 is usually manufactured in the form of a fine square of 16 μm, and is inclined at any one of +10 degrees to -10 degrees by the axis 7 moving at a predetermined angle. Move. The light incident on the micromirror 5 is totally reflected and proceeds to the projection lens 11. The light reflected toward the projection lens 11 is reflected on the screen 15 through the projection lens 11 so that the state of the screen 15 becomes a white state. In other words, by moving the square micromirror 5 diagonally to ± 10 degrees in a diagonal direction by using an electric field generated by an externally applied voltage, it is possible that the light totally reflected from the light source 9 is reflected to the screen 15. Can be controlled. That is, the screen 15 can be turned ON / OFF at high speed using the micromirror 5.

The illumination optical system of the DLP including the integrator is shown in FIG. 2 in detail.

The DLP illumination optical system includes a light source for generating light, a color wheel 17 for transmitting light of a specific wavelength band, an integrator 19 for equalizing light distribution of light passing through the color wheel 17, and an integrator. First and second lenses 21 and 23 for condensing the light passing through 19, the DMD 25 for reflecting or transmitting the light in a specific direction, and other devices.

The light source is composed of a lamp 9A for generating light and an ellipsoidal mirror 9B for totally reflecting the light generated by the lamp 9A to the front. The light generated from the lamp 9A is focused by the ellipsoidal reflector 9B and focused on the color wheel 17 and then transmitted through the color wheel 17.

The color wheel 17 sequentially transmits red, green, and blue light while rotating by a motor (not shown). The light separated by the color wheel 17 is incident on the integrator 19.

The integrator 19 has a rectangular parallelepiped shape as shown in FIG. 3, and the incidence plane is inclined and the inclined plane is inclined because the incidence plane is larger than the exit plane. . The integrator 19 totally reflects the incident light several times in the interior, so that the emitted light has a uniform light distribution on the screen.

This is described in detail as follows. The condition under which the light incident to the inside of the integrator 19 is totally reflected is expressed by Equation 1 below. Equation 1 shows Snell's law.

Here, n and n 'means the refractive index, θ means the angle of incidence of light and θ' means the refractive angle of light.

In general, when the total incident light enters a material (n) having a large refractive index and a material having a small refractive index (n '), when the incident angle θ is greater than a certain angle, that is, a critical angle, all the light is reflected at the interface between the two materials. Discarded means that no refracted light exists. When light enters the medium n having a high refractive index and the medium n 'having a small refractive index, the refractive angle θ' becomes larger than the incident angle θ. At this time, as the incidence angle θ becomes larger, the refraction angle θ 'also increases, and the incidence angle θ when the refractive angle θ' becomes 90 ° is called a critical angle. That is, the incident light is totally reflected when the incident angle θ of the light is greater than or equal to the critical angle. For example, when the light goes from glass to air, the critical angle is 42 °, and if the incident angle is larger than the critical angle, all the light is reflected off the inner surface of the glass and does not go out into the air. Therefore, when the incident angle [theta] of the light incident on the integrator 19 is larger than the critical angle, the light is totally reflected inside the integrator 19 and emitted.

In this way, the light incident on the integrator 19 propagates inside the integrator 19 to uniformly travel to the first and second lenses 21 and 23.

The first and second lenses 21 and 23 serve to focus light. Accordingly, the light passing through the integrator 19 is focused by the first and second lenses 21 and 23 and proceeds to the DMD 25.

The DMD 25 adjusts the inclination angle by the driving voltage to reflect only the necessary amount of incident light toward the projection lens 11 to project it onto the screen 15, and reflects the remaining unnecessary light toward the absorber plate 13. In this way, the DMD 25 adjusts the amount of light according to the inclination of the micromirror to display an image.

As the size of the DMD decreases in size, the DLP illumination optical system reduces the size of the light distribution incident on the DMD while minimizing the size of the exit surface of the integrator 19 to maximize the light efficiency. However, while reducing the size of the exit face of the integrator 19, the size of the incident face is also reduced, resulting in low light efficiency. That is, in order to increase the light efficiency in the DMD, the size of the incident surface of the integrator 19 should be increased. This is because the amount of light irradiated to the DMD 25 is increased by the incident surface into which light is incident on the integrator 19, that is, the size of the incident surface is increased, resulting in an increase in the light efficiency of the incident surface of the integrator 19. This is because the smaller the size, the smaller the amount of light in the DMD 25. As a result, the incident surface of the integrator 19 is larger than the exit surface, so that the integrator 19 has an inclined surface. However, when the inclined surface of the integrator 19 is inclined, the total reflection angle of the light becomes large.

In fact, FIGS. 4 to 6 show the distribution of light exit angles according to the inclination of the integrator 19. 4 to 6 show the distribution of the emission angles by placing a receiver on the exit surface of the integrator when the inclination angles of the integrator are 1, 1.2, and 0.625, respectively.

Referring to FIG. 4, assuming that the length of the integrator 19 is 50 mm, and the inclination of the inclined surface of the integrator 19 is 1, the light efficiency is 54.610%. As shown in FIG. 5, when the inclination degree of the inclined surface of the integrator 19 is 1.2, the light efficiency is 63.866%. That is, it can be seen that the light efficiency increases as the inclination of the inclined surface of the integrator 19 increases. On the other hand, as shown in FIG. 6, when the inclination of the inclined surface of the integrator 19 is 0.625, it can be seen that the light efficiency is lowered to 45.058%.

As a result, the light distribution of the light exiting through the exit surface of the integrator 19 becomes uneven, and the light traveling toward the front surface is returned or scattered at the exit surface, resulting in light loss.

Accordingly, it is an object of the present invention to provide an integrator of an illumination system for an image projection apparatus which can improve the light efficiency by reducing the total reflection angle of the integrator.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a diagram showing driving characteristics of DLP (Digital Light Processing) using an integrator in a conventional optical projection apparatus illumination optical system.

2 is a cross-sectional view showing an illumination optical system of a DLP using an integrator.

FIG. 3 is a perspective view of the integrator shown in FIG. 2. FIG.

4 is a diagram showing a total reflection angle distribution when the inclination of the inclined surface of the integrator shown in FIG. 2 is zero;

5 is a diagram showing a total reflection angle distribution when the inclination of the inclined surface of the integrator shown in FIG. 2 is 1.2.

FIG. 6 is a diagram showing a total reflection angle distribution when the inclination of the inclined surface of the integrator shown in FIG. 2 is 0.625. FIG.

7 is a cross-sectional view illustrating an illumination optical system of a DLP including an integrator according to a first embodiment of the present invention.

FIG. 8 is a perspective view of the integrator shown in FIG. 7. FIG.

FIG. 9 is a diagram showing a total reflection angle distribution of the integrator shown in FIG. 7. FIG.

10 is a perspective view illustrating an integrator according to a second embodiment of the present invention.

11 is a perspective view illustrating an integrator according to a third embodiment of the present invention.

12 is a perspective view illustrating an integrator according to a fourth embodiment of the present invention.

13 is a perspective view illustrating an integrator according to a fifth embodiment of the present invention.

14 is a perspective view illustrating an integrator according to a sixth embodiment of the present invention.

15 is a perspective view illustrating an integrator according to a seventh embodiment of the present invention.

16 is a perspective view illustrating an integrator according to an eighth embodiment of the present invention.

Fig. 17 is a diagram showing a projection device of a three-plate liquid crystal display device including an integrator.

<Description of Symbols for Main Parts of Drawings>

1: Blackboard 3: Electrode

5: micromirror 7: axis

11, 145: projection lens 13: absorption plate

15: Screen 17: Color Wheel

19,45,61,71,81,91,101,111,113,123: Integrator

21, 23, 47, 49, 125: Lens 25, 51: DMD

121: light source 127,139: dichroic mirror

129: total reflection mirror 133,137,143: PBSP

140R, 140G, 140B: Liquid Crystal Panel 135: Dichroic Prism

In order to achieve the above object, the integrator of the illumination optical system of the image display device according to an embodiment of the present invention comprises a light incident surface to which light is incident, a light exit surface to which the light is emitted, and at least two inclined surfaces having different inclinations. Equipped. The inclined surfaces having different inclination degrees are connected with a step, and the light incidence surface is larger than the light incidence surface. The inclined surface close to the light incidence surface is narrowed by a gentle curve, and the inclined surface close to the light incidence surface is gentle. The integrator of the image display apparatus illumination optical system according to another exemplary embodiment of the present invention includes a first inclined plane having an inclination from which an area is reduced from a light incidence plane and light from an end of the first inclined plane. And a second inclined plane having an inclined area that increases in area to the exit plane. The incidence plane of the integrator may be any one of a circle, an ellipse, and a quadrangle. It will be apparent from the description of the embodiment with reference to.

Hereinafter, exemplary embodiments of the present invention will be described with reference to FIGS. 7 to 16.

7 is a diagram illustrating an illumination optical system of a DLP including an integrator according to a first embodiment of the present invention.

Referring to FIG. 7, the DLP illumination optical system includes a light source for generating light, a color wheel 43 for transmitting light of a specific wavelength, and an integrator 45 for equalizing light distribution of light passing through the color wheel 43. ), First and second lenses 47 and 49 for condensing light passing through the integrator 45, and a DMD 51 for reflecting light in a specific direction.

The light source is composed of a lamp 41A for generating light and an elliptical reflector 41B for totally reflecting the light generated by the lamp 41A to the front. The light generated from the lamp 41A is totally reflected by the ellipsoidal reflector 41B and condensed by the color wheel 43. The color wheel 43 sequentially transmits red, green, and blue light while rotating by the motor. The light separated by the color wheel 43 is incident on the integrator 45.

As shown in FIG. 8, the integrator 45 has a shape in which the size of the light incident surface 53 is larger than that of the emission surface 59. When the size of the incident surface 53 is larger than the size of the emission surface 59, the amount of light incident increases, so that the amount of emitted light increases. In addition, the integrator 45 is formed such that the inclined surface has at least two or more inclinations. That is, the first inclined surface 55 is formed to decrease the inclination from the incident surface 53, and the second inclined surface 57 is formed to increase the inclination at the end of the first inclined surface 55. As such, when the inclination of the inclined surface is changed while increasing the size of the light incident surface of the integrator 45, the light emission angle is reduced to increase the light efficiency.

For example, as shown in FIG. 9, when the inclination of the first inclined surface 55 of the integrator 45 is 0.625 and the inclination of the second inclined surface 57 is 1.2, the light efficiency increases to 63.09%. The exit angle does not increase.

The light incident on the integrator 45 is totally reflected inside the integrator 45 and uniformly travels to the first and second lenses 47 and 49 so as to be uniformly distributed on the screen. The first and second lenses 47 and 49 serve to focus light. Light passing through the integrator 45 is focused by the first and second lenses 47 and 49 and proceeds to the DMD 51. The DMD 51 serves to reflect the light at a specific angle by adjusting the micromirror by an external voltage, and the DMD 51 reflects the light from the first and second lenses 47 and 49 to the projection lens 53. B).

As described above, another embodiment according to the shape of the integrator 45 having the inclined surfaces having different inclinations is as follows.

Referring to FIG. 10, in the integrator 61 of the DMD device according to the second exemplary embodiment of the present invention, the size of the incident surface 63 is greater than that of the emission surface 67, and the incident surface 63 and the emission surface The inclined surface 65 in between narrows to a gentle curve from the incidence side to an arbitrary intermediate point and widens to a gentle curve from its midpoint to the exit side.

As shown in FIG. 11, the integrator 71 of the DLP according to the third embodiment of the present invention includes a first inclined surface 75 and a first inclined surface 75 formed in a direction in which the inclination increases from the incident surface 73. It consists of a second inclined surface 77 formed in the direction of decreasing inclination at the end of. At this time, the size of the incident surface 73 is designed to be larger than the size of the exit surface 79.

As shown in FIG. 12, the integrator 81 of the DLP according to the fourth embodiment of the present invention changes the slope of the inclined surface 85 so that the area gradually increases and decreases along the curve. The size of the entrance face 83 is designed to be larger than the size of the exit face 87.

As shown in FIG. 13, the integrator 91 of the DLP according to the fifth embodiment of the present invention includes a first inclined surface 95 and a first inclined surface that are inclined in a direction in which the area is narrowed from the incident surface 93. It consists of the 2nd inclined surface 97 which inclines in the direction which expands an area from the end of 95 to an exit surface. Here, the first inclined surface 95 is designed to have a step higher than the second inclined surface 97, and the size of the incident surface 93 is designed to be larger than that of the exit surface 99.

Referring to FIG. 14, the integrator 101 of the DLP according to the sixth embodiment of the present invention may include a first inclined surface 105 and a first inclined surface 105 that are inclined in a direction in which an area becomes narrower from the incident surface 103. It consists of a second inclined surface 107 which is inclined in the direction in which the area from the end of the) to the exit surface. Here, the first inclined surface 105 is designed to have a step lower than the second inclined surface 107, and the size of the incident surface 103 is designed to be smaller than that of the exit surface 109. At this time, although the size of the incident surface 103 is designed to be smaller than the size of the exit surface 109, since the light incident inside the integrator 101 is totally reflected and emitted, it is not a big problem in terms of the light efficiency. Can be reduced.

Referring to FIG. 15, the integrator 111 of the DLP according to the seventh embodiment of the present invention has an incidence plane having an ellipsoid and an exit plane having a quadrangular shape. Alternatively, as illustrated in FIG. 16, the incidence plane of the integrator 113 of the DLP according to the seventh embodiment of the present invention has a circular shape, and the emission plane has a rectangular shape.

Although the shapes of the integrators described above are all different, they have the same effect of improving the light efficiency since the emission angle of the emitted light is reduced.

Fig. 17 is a diagram showing a projection device of a three-plate type liquid crystal display device to which the integrators described above are applied.

Referring to FIG. 17, a projection apparatus of a three-plate liquid crystal display including an integrator includes a light source 121 for generating light, an integrator 123 for uniformizing light distribution, and a focus for condensing light. Lens 125, first and second dichroric mirrors 127 and 139 for reflecting or transmitting light according to the wavelength to separate light, and a total reflection mirror 129 for total reflection of light. ) And first to third polarizing beam splitter prisms (hereinafter referred to as "PBSPs") for converting polarization states of light separated into red (R), green (G), and blue light (B) (133). And 137 and 141, and liquid crystal panels 140R, 140G, and 140B positioned on optical paths of red, green, and blue light, respectively.

The light source 121 generates light and propagates the light toward the integrator 123. The integrator 123 has a shape where the size of the light incident surface is larger than the size of the emission surface and the inclined surface has at least two inclinations. The integrator 123 is implemented in the embodiments of FIGS. 8 and 10 to 16 to reduce the total reflection angle in the inside and reduce the emission angle to increase the amount of light traveling to the focusing lens 125.

The focusing lens 125 focuses the incident light from the integrator 123 on the first dichroic mirror 127. The first dichroic mirror 127 transmits blue light among the light focused and incident from the focusing lens 125 and reflects light having a wavelength longer than that of blue light, that is, red and green light.

The total reflection mirror 129 propagates the blue light separated from the first dichroic mirror 127 toward the first PBSP 133. The first PBSP 133 reflects or transmits the blue light incident from the total reflection mirror 129 according to the polarization component of the light. The blue liquid crystal panel 140B is a reflective liquid crystal panel and reflects the blue light incident from the first PBSP 133 to travel toward the dichroic prism 135 via the first PBSP 133.

The second dichroic mirror 139 transmits red light among the light incident from the first dichroic mirror 127 and reflects green light. The second PBSP 137 reflects or transmits the green light reflected from the second dichroic mirror 139 according to the polarization component of the light. The green liquid crystal panel 140G is a reflective liquid crystal panel and reflects the green light incident from the second PBSP 137 to travel toward the dichroic prism 135 via the second PBSP 137.

The third PBSP 143 reflects or transmits the red light transmitted from the second dichroic mirror 139 according to the polarization component of the light. The red liquid crystal panel 140R is a reflective liquid crystal panel and reflects the red light incident from the third PBSP 143 to advance toward the dichroic prism 135 via the third PBSP 143.

Accordingly, the dichroic prism 135 reflects blue and red light incident through the first and third PBSPs 131 and 143 toward the projection lens 145 and also via the second PBSP 137. By passing the incident green light toward the projection lens 145, red, green, and blue images are synthesized. The projection lens 145 enlarges and projects an image incident from the dichroic prism 135 on the screen.

As described above, the integrator used in the illumination optical system of the image projection apparatus according to the present invention can increase the light efficiency by having at least two inclined surfaces having different inclinations. Furthermore, the integrator used in the illumination optical system of the image projection apparatus according to the present invention can prevent the total light reflection angle of the light from increasing as the light travels therein, thereby preventing the light efficiency from dropping.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

Claims (6)

In the integrator to have a uniform light distribution in the image projection apparatus illumination optical system, The integrator, A light incident surface to which light is incident, A light exit surface from which the light is emitted; At least two slopes having different slopes, And an inclined surface having different levels of inclination, wherein the light incidence surface is larger than the light emission surface. delete delete The method of claim 1, The inclined surface close to the light incident surface is narrowed to a gentle curve, And an inclined surface close to the light exit surface is wider in a gentle curve. In the integrator to have a uniform light distribution in the image projection apparatus illumination optical system, The integrator, A first inclined plane having an inclination of increasing in area from the light incidence plane, And an inclined second inclined surface having an area reduced from an end of the first inclined surface to a light emitting surface. The method according to claim 1 or 5, And an incidence surface of the integrator is any one of a circle, an ellipse, and a rectangle.